a sphere
vertices
A Sphere.
A plane figure has 2 dimensions (length & width$ & is represented by a flat surface. It takes 3 noncollinear points to make a plane. A solid figure has 3 dimensions. It not only has length & width but also depth. It takes 4 noncoplaner points to make space
A sphere
circle
They are called equidistant points and form points on a sphere for a solid or a circle on a plane figure.
It is not a solid figure because an icosagon is a polygon with 20 sides
A solid sphere perhaps?
Vertices are points in a solid, or 3-D figure, where edges meet.
Three
A many sided planar figure is a polygon. A many sided solid is a polyhedron.